1. Field of the Invention
This disclosure is related to the field of systems for the monitoring of mass transit systems, such as light rail transit, trains, trams and metros, whose routes are integrated with and/or intersect roads, pedestrian crossways or other vehicular or human passageways for ingress or egress.
2. Description of Related Art
Due, in part, to an rising concern over increasing greenhouse gas emissions associated with individual motor vehicle commutes, the ever-escalating prices of gasoline and the increased traffic flow and congestion associated with rising metropolitan populations, mass transit systems have generally seen an increase in ridership in recent years. With this rising ridership comes an increase in the number of mass transit units and routes and, thus, an increased presence of mass transit commuter vehicles on or near motor or pedestrian throughways. For example, the Houston METRO operates about seven and one half (7.5) miles of surface rail line for light rail transit (LRT). This LRT system is integrated with and operates on Houston city streets and currently carries about 40,000 riders a day.
Integrating the increase in ridership and mass transit units on LRT lines with existing motor vehicle and pedestrian streets and walkways creates obvious logistical and operating concerns. Accordingly, reliable and effective maintenance and monitoring systems for operating mass transit systems, such as LRT, are becoming increasingly important. Systems with the capability of monitoring non-vital signal elements of street-running LRT systems with increased reliability and decreased operating and maintenance costs are therefore desirable.
Important non-vital signal elements to be monitored by such systems include, but are not limited to, on-board and station announcements (i.e., communication to passengers as to when an Light Rail Vehicle (LRV) is approaching a station or stop); traffic signal prioritization and pre-emption; grade crossing initiations; automatic vehicle location (AVL); route selection at interlockings; maximum speed limit control; headway maintenance; and indications of a LRV on the wrong track proceeding in the wrong direction. Another non-vital signal element that is of particular concern is intersection stop bar infringement. An intersection stop bar is the defined stopping point for a vehicle or individual at an intersection. Stop bars can be designated by broad white lines on the rail or road or more tangible barriers such as retractable gates or bars. With the increasing interaction between LRVs and motor vehicle and pedestrian traffic flow at intersections, the number of incidents in which an LRV operator has passed a bar stop signal and improperly proceeded into the intersection, thus causing an accident, has increased. A monitoring system with the capability to monitor and discipline operators in a way that is fair and impartial would be key step in reducing this problem.
Currently, a variety of different control and coordination systems are utilized to monitor LRT systems. One basically utilized mechanism is train-to-wayside technology. In this system, the movement of LRVs in the LRT route grid is monitored by an embedded track sensor system. Generally, this technology has the capability to monitor some non-vital signal elements such as: announcements in a station that a train is coming; next-station messages onboard LRVs; and route selection at the terminal stations.
However, there are serious problems associated with the currently utilized TWC systems. Delays and significant maintenance costs have been incurred by city transit systems that utilize TWC, primarily related to the water infiltration of TWC circuit boards. For example, in areas of Houston where the TWC system was utilized, upon incidences of heavy rain, the streets would frequently fill with water which overflowed the curbs and covered the embedded track. The water would then seep through openings in the concrete, causing water damage to the circuit boards. As replacement boards for the TWC system cost approximately $1,000 each, the cost of annual maintenance upon metropolitan mass transit systems to repair and protect the TWC system from water damage became extremely high, a cost that will only grow as LRT routes and lines increase in number. In addition to the high maintenance costs associated with the currently utilized TWC system, it also suffers from an inability to monitor certain non-vital elements and does not provide the flexibility of changing detection zones as the monitoring zones are specifically tied to the specific tangible location of the embedded circuit boards. Accordingly, there is a need for an LRT monitoring and operating system which is capable of monitoring a wide variety of non-vital elements, while also eliminating embedded loops in the trackway and reducing the need for other wayside detection equipment.